Waveguide window



Feb. 7, 1961 M, R, HAMlLToN ErAL 2,971,172

WAVEGUIDE WINDOW 2 Sheets-Sheetl 1 Filed Aug. 20. 1959 INVENTOR. MILTON R. HAMILTON BYLOUIS S. 4 TREMBLAY z@ ATTORNEY Feb. 7, 1961 M. R. HAMILTON ErAL 2,971,172

WAVEGUIDE WINDOW Filed Aug. 20, 1959 2 Sheets-Sheet 2 INVENTOR. MILTON R. HAMILTON LOUlS S. TREMBLAY ATTORNEY Unit d WAVEGUHDE WlND W Filed Aug. 20, 1959, Ser. No. 835,025

2 Claims. (Cl. S33-9S) The present invention relates to electromagnetic waveguide systems and more particularly to dielectric windows for use in such systems transmitting high power microwave energy;

Conventional prior art dielectric windows are employed in waveguide structures to provide hermetically sealed enclosures containing ionizable atmospheres to control transmission of energy. These structures are referred to as transmit-receive and miti-transmit-receive devices for use in single antenna radar systems. During transmission of high power energy an intense gaseous discharge is initiated within the enclosure which creates serious problems affecting operational life and eiciency. in addition, the high power energy impinging on the outer face of prior art windows may cause problems of arcing. Foremost, amongst the operational problems are the generation of heat within the enclosure and thermal shock together with depositing of metallic particles on the dielectric window surfaces. All these phenomena contribute to window cracks, leaks and erratic behavior.

It is customary in prior art window design to deline a resonant opening Vby means of a metallic frame or coating and the metallic means are disposed on the inner and outer surfaces either in the area of the ion bombardment within the discharge area or in the area of intense electric eld at high transmitter powers. The present invention has therefore, for its primary object the provision ot a novel waveguide window for use in microwave electromagnetic energy transmission devices and/or systems. Another object of the invention is to provide a waveguide window having no metallic structure disposed either on the inner or outer surfaces thereof.

Further objects, features and advantages will become apparent after consideration of the following detailed description and accompanying drawings, in which:

Fig. l is an end view partially cut-away of an embodiment of the invention mounted at one end of a section of waveguide;

Fig. 2 is a cross-sectional view along the line 2-2 in Fig. l; and

Fig. 3 is an exploded view of the embodiment of the invention.

As shown in Figs. l and 2, the invention is directed to a Window assembly 1 adapted for mounting at an end of a waveguide section 2 having a mounting ange 3 secured adjacent to said end. Such structure will be employed to define hermetically sealed enclosures for transmit-receive or anti-transmit-receive devices by providing similar windows at each end of the waveguide section. in other applications such windows will be employed to separate certain sections of waveguide which may be maintained under pressure or contain different atmospheres.

In accordance with the present invention, referring also to Fig. 3, the window assembly 1 comprises, iirst, a dielectric member 4 of a ceramic material having an overall configuration slightly larger than the internal dimensions of the associated waveguide sections 2. A thin layer of a metallized coating 5 covers only one planar surface of 2,971,172 Patented lieb. 7, i961 the ceramic member with the exception of an area deining a resonant opening 6 which is pervious to electromagnetic microwave energy. Another dielectric member 7 of a similar material with a metallized coating 8 dening an opening 9 is provided in a similar manner, however, the coated surface in this instance is in face-to-face relationship with the coating on member li. yinterposed between the ceramic members is a thin metallic member iii, of a metal such as copper7 having a matching opening i1.

The window components are assembled and brazed together to form a vacum tight composite sandwicl1-type assembly. A metallic channel member i2 is also brazed aiong the peripheral edges or' the assembly to provide for a metai-to-metal seal to waveguide section 2 and flange 3, as shown in Fig. 2.

t will be noted that the window of the invention presents a continuous dieectric path on the inner and outer surfaces when the assembly is mounted in a waveguide structure. The resonant opening to permit passage of microwave energy within predetermined frequency ranges is now defined within the assembly without eX- posure of any metallic surfaces to the transmitter energy or intense gaseous discharge. As a result, the sputtering problem has been considerably reduced and the life of associated discharge devices increased.

The embodiment of the invention has been described with specific reference to a particular configuration, however, in many applications other conligurations will be equally effective, such as a circular window for circular hollow pipe transmission lines. lt is to be understood, therefore, that the foregoing description is illustrative only and the scope of the invention will be dened in the appended claims.

lf'i/hat is claimed is:

1. A resonant window assembiy adapted for mounting in hollow pipe electromagnetic waveguide structure comprising a unitary assembly formed by a pair of dielectric members and a metallic member disposed therebetween, said assembly being characterized by the disposition of a metallized coating on confronting planar surfaces of said dielectric members and the bonding of said coated surfaces and metallic member to form a vacuum-tight seal, said assembly having a centrally disposed uncoated area dened by the metallized coating on each dielectric member and an opening dened in said metallic member in register with the uncoated areas, said assembly being further characterized by the absence of any dielectric material extending within the opening in said metallic member.

2. A resonant window assembly adapted for mounting in hollow pipe electromagnetic waveguide structure cornprising a rst dielectric member of a ceramic material, a metallized coating covering one face thereof defining a resonant opening, a second dielectric member of a ceramic material having a metallized coating covering one face thereof defining a resonant opening, said coated surfaces being disposed in face-to-face relationship, with a metallic member defining a resonant opening interposed between said ceramic members, said ceramic and metallic members being bonded together to form a composite vacuumtight assembly characterized by the absence of any metallic surfaces on the inner and outer planar sides thereof when Said assembly is mounted in waveguide structure and the absence of any dielectric material extending within the resonant opening.

References @iisd in the tile of this patent UNITED STATES PATENTS 2,770,784 Hatch Nov. 13, 1956 2,869,086 Curtis Jan. 13, 1959 2,879,485 Carter Mar. 24, 1959 

